Such a machine is known from U.S. Pat. No. 6,539,710 B2. The first section shows an externally toothed gear wheel that interacts with an internally toothed ring. Pressure pockets are formed between the gear wheel and the ring, said pressure pockets being either supplied with pressure fluid or connected to a low-pressure area via a rotary valve slide arrangement. The gear wheel is connected to the shaft via a cardan shaft. The gear wheel engages a crank pin that transmits the orbiting movement of the gear wheel to a sensor shaft.
U.S. Pat. No. 4,593,555 describes a hydraulic engine in which a pressure sensor is used to detect the rotation speed of the shaft.
U.S. Pat. No. 6,062,123 describes an auxiliary force supported steering arrangement with an engine and a sensor that detects a position of a steering handwheel. The sensor is arranged to be radial to the axis of the steering handwheel shaft.
DE 198 24 926 C2 describes a further hydraulic steering arrangement, in which a front side of an inner control slide is provided with a row of teeth which can be detected by a sensor.
DE 10 2005 036 483 B4 describes a hydraulic rotary machine, whose shaft is provided with a transmitter, whose circumference comprises a toothed structure with teeth and grooves. In the housing is arranged a transmitter that directs a light beam towards the threaded structure. From the threaded structure the light beam is reflected to a receiver.
In many application fields for such machines, in particular hydraulic rotary machines, sensors are required to enable steering of the machine with sufficient accuracy, for example in connection with a connected diesel engine, in order to save energy.
The sensor arrangements in the machines mentioned in the introduction have proved their worth. However, frequently a relatively complicated integration of the sensor is required. The sensor will then often be in a position, in which it is actually disturbed. If the sensor is arranged in a position, in which it is disturbed less, the problem occurs that it cannot directly detect the rotation of the shaft, but is connected to the shaft via several engagement points which are causing slack. A similar problem occurs, when the shaft can get twisted, for example because of large torques inside the movement chain.